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Proto Pedal for DIY Guitar Effects

Designing and building your own guitar effects is a great way to combine a passion for electronics and guitar. However, when testing new designs, I found the fragile circuit on the solderless breadboard was difficult to connect to patch cords and control the potentiometers.

The answer was simple: build a guitar pedal just for prototyping!

UPDATE: The wire pin sockets I was using for signal in/out broke on me, so I made use of the spare holes and put in binding posts for them. Definitely a great improvement.

Step 2: Schematic and Design

The circuitry inside the pedal is mostly incomplete, because you will be hooking up components on the breadboard on the surface.

The potentiometers and switches are all wired up to connectors so that they can be used on the breadboard however you want. DC power coming in from the power brick is connected to the binding posts, and the footswitch controls signal routing and power.

The box will be comprised of two three-sided segments which will fit together like a handshake. My plan was originally to do a 5-sided box, but that turned into major troubles and I didn't like the outcome. I redid it doing two three-sided shapes and it was a much better result. For this reason, a couple images depict the original design and attempt, and the rest are of the two piece that worked much nicer. The old ones are included just for some additional information.

My template in the photos is for a 5-sided box, but it can be very easily followed for 3-sided shapes instead. I've drawn over top of it to show the shapes and holes you need for the two 3-sided shapes.

The dimensions are 8.5"x4"x1", using 1/4" graphing paper to make everything nice and easy. The pots, switches and binding posts are in a line across the top, spaced "1 apart each. The footswitch and LED are 1" from the nearest side and 1" apart. Take into account the dimensions of your breadboard before punching and drilling holes.

Follow the image below. It shows the flat shape of the two segments we want to make, and outlines the holes to drill.

Cut out the design and tape it to your aluminum sheet. Mark your cutting lines around the perimeter with a sharp metal implement. A nail or scribing tool works nicely.

Mark the center of each component hole with the center punch and hammer. Remove the template.

Step 3: Cut, Drill and Fold

First, cut out the two pieces using tin snips, a nibbler or a notcher. Tin snips are the best route if you don't have more heavy machinery, but a big metal shear and notcher is ideal.

Once its cut out, drill appropriately sized holes for each component. You can use a caliper to find the diameter of each, then drill with the next size up imperial drill bit.

Also drill a line of 1/4" diameter holes beneath the potentiometer holes, and file them out to make a slot for potentiometer and switch wires to pass out of.

Using the break press, bend the flanges at the end of each 3-sided piece, then make the bends to separate the sides from the top. Repeat for the second piece.

Now, fit them together with a little bit of flexing. Drill four tiny holes in the top panel along the top and bottom, near the corners. The hole should be slightly smaller diameter than the self-tapping screws you have to hold the box together. Once a hole is drilled through the top piece and through the second piece below (but not all the way through the box, of course) then disassemble the halves and drill out the top hole again using a bit slightly larger than your screw diameter. Now you will be able to screw the two halves together firmly once everything is done.

Step 4: Paint and Assembly

Spray on a coat of paint to make it pretty, and let it cure.

Insert all the components through their respective holes and affix with nuts. The small wire pin holes will need to be cut to shape with wire cutters and hot-glued in place from beneath.

Solder all the connectors and things together according to the schematic from Step 2.

Plug in 9V from a wall adapter and hit the footswitch, you should see the LED turn on and a voltmeter will show that 9V exists on the binding posts. If so, great job!

Unplug the unit and screw the two halves together. You're done!

Step 5: Conclusion

Now, you'll notice I didn't include the test pots and switches like I planned for. I decided, circuits are so diverse, and you'll always actually need the pots later for the actual assembly of whatever you're prototyping, that maybe affixing permanent pots isn't such a great idea. Maybe a permanent master volume control would be a good improvement, but I had a change of heart against the fixed pots. The slots and holes are still great for future improvements and built-in features though, definitely.

This design can definitely be modified to suit any specialized prototyping purpose. The exact same thing sans footswitch and signal jacks would be perfect as a regular prototyping platform. Incorporating a power supply inside the unit would be very cool. There's lots to tinker with here.

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17 Discussions

I think you might want to give a shout out to Beavis Audio Research, the maker of the commercial Beavis Board. http://www.beavisaudio.com/bboard/projects/ Also a great source for breadboard guitar FX project layouts!

While the Beavis Board is the only real commercial Proto-pedal of sorts, the idea of mounting a breadboard to a power supply, or mounting it to a piece of wood to include extra parts/jacks/switches is not original to Beavis Audio. I also did not claim to invent guitar effect-focused prototyping platforms. The Beavis board is a nice product though, albeit slightly overpriced. Thats what DIY is for though, isn't it?

Congrats on your super cool prototype box, and for sharing it with the diy community. Regarding the slightly overpriced comment, I'd extend this challenge to all comers: try to build the beavis board in quantity, source all the parts, do the packaging, QA and support and see if you can turn a profit at the beavis board price point. Not something I'd recommend for the faint of heart :) However, that's not the point. It is all about DIY. That's why all my guides, projects, articles and in-depth how-to resources are, and always will be, free to all. Thanks for your great instructable! -beavis

Certainly anyone selling something for the DIY community is just offering a DIY-style project that is preassembled for the people who are interested but don't have the tools or the skills yet. The beavis board is a teaching implement, since it comes with projects and components, and it is a really nice and reasonable buy for the novice who wants to get into DIY guitar effects.

If you don't have an engineering background, or can't read schematics, this information is invaluable to the hobbyist.

I do not own a Beavis Board myself as I built one using the plans which Dano Beavis makes freely available on his site! The "overpriced" comment is unnecessary. While I appreciate your instructable, especially the enclosure layout, Beavis has had information on the web about this sort of thing for several years and, more importantly, offers a source of information as to "what you do with it" once you have built this project.

Great simple idea! You're so right about pots and switches being a pain. Perfect solution. I'd post links to some other schematics websites, but I haven't dug them out of my new computer. (links didn't migrate well) Some quick searching will give you all you can handle for a long time though!

Would be good if you linked to some of your favourite guitar pedal websites... I have had a look once before, but it would be good to learn the theory behind the pedal. That way it is easier to design them, and make new effects.